Hypersonic Crossflow Instability

Under the auspices of NATO STO AVT-240: "Hypersonic Boundary-Layer Transition Prediction", this paper describes the results of close collaborations among the authors toward the fundamental understanding and modeling of the instabilities associated with three-dimensional boundary layers in hypersonic flight. Specifically, the focus is directed toward the crossflow instability. A common straight circular cone geometry is analyzed for M = 5.91-6 and Re' = 9.8-10.1 x 10(6)/m from both a computational and experimental perspective using methods that are unique to each facility and methodology. Disturbance wavelength and trajectory, surface roughness, and the use of quiet wind tunnels are just a few items found to be key factors in the investigation of the crossflow instability. Quiet tunnels allow experiments to be performed in a disturbance environment comparable to that expected from flight, and the combination of different facilities and computations displays a comprehensive analysis that would be unobtainable from any individual approach alone.